Scientech Stresswave SRV Leak Detectionfamos.scientech.us/PDFs/2015_Symposium/Scientech... · Scientech Stresswave SRV Leak Detection ... Piezoelectric accelerometer ... Valve Leak

1 | September 17, 2015 | © Curtiss-Wright

Scientech Stresswave SRV Leak Detection

Scientech Symposium 2015


SRV

SRV = Safety Relief Valve “A pressure relief vessel which automatically releases a

substance from a boiler, pressure vessel or other system, when the pressure exceeds preset limits.”


Agenda

Stresswave Technology Overview Valve Leakage Detection Project Valve Testing Data SRV Maintenance Examples Using Stresswave Questions/Comments


What Are Stresswaves?

Stresswaves are ultrasonic acoustic energy impulses (~40kHz) that radiate through solid,

liquid and gas in all directions.


Causes of Stresswave Energy

FRICTION – Contact Pressure – Contact Surface Area – Roughness - Smoothness – Relative Surface Speeds – Lubricant Condition – Operating Load – Operating Speed

SHOCK & IMPULSE – Impact Velocity – Damage/Imperfection

Size – Depth – Area

Gas or Fluid FLOW

– Leakage – Turbulence – Cavitation


Stresswave Basics

Stresswave principle: “Resonance is good!” Natural frequency of valve metal structures ~ 40kHz Structure-borne Ultrasonic Frequencies

Low amplitude Easily reflected Quickly damped


Stresswave Basics

SWE = Stress Wave Energy

A unit of measure based on the energy contained within the raw sensor signal

Increases in orders of magnitude as stress and friction increase.


Stresswave Energy Sensor

Piezoelectric accelerometer Designed specifically to utilize the natural resonant

frequency of the piezoelectric crystal element The sensor incorporates an internal filter to reduce low

frequency noise INTRINSIC SAFETY:

Class I, Division 1, Groups A, B, C & D Process Temperature -50°C to 120°C Radiation hardening: manufacturer is recommending 100

Mrad test


Valve Leak Detection Project

Exelon was experiencing leakage with their Target Rock SRVs causing unscheduled outages

Exelon partnered with Scientech in 2008 to use Stresswave technology to detect valve leakage

Testing of the technology was performed at the NWS valve testing facility in Spartanburg, SC

A permanent Stresswave system was installed in 2009 and all Exelon valves that are refurbished at NWS go through the Stresswave test


NWS Testing Summary – Exelon Valves

0 2 17

30

80 71

64

0

10

20

30

40

50

60

70

80

90

2008 2009 2010 2011 2012 2013 2014

TOTAL VALVES TESTED USING STRESSWAVE TECHNOLOGY


NWS Testing Summary – Exelon Valves Using Scientech

0 2

17 20 34

20 23

0

29

36 21

0

10

20

30

40

50

60

70

80

90

2008 2009 2010 2011 2012 2013 2014

PORVsPSVsERVsMSSVsTR 3-Stage

71 64

17

30

80


NWS Testing Summary – Exelon Valves Using Scientech

116

86

0

20

40

60

80

100

120

140

TR 3-Stage MSSVs ERVs PSVs PORVs

PORVsPSVsERVsMSSVsTR 3-Stage

32

5

Exelon has Certified 264 SRVs on +1,000 Psig Steam in 6 Years

25


Valve Leak Detection Project

In 2013 Exelon and Scientech were awarded a NEI TIP (Top Industry Practice) Award for Stresswave testing of Limerick and Peach Bottom GS MSRVs

“The TIP Awards highlight the nuclear industry’s most innovative techniques and ideas”


Exelon Benefits

Save $7M/yr. in SRV unscheduled outages

Save $750K/yr. – 50% reduced SRV scheduled maintenance at LGS

Reduced SRV SWE average by 200% with improved SRV repair methods


Valve Leak Detection – Sensor Placement












Valve Leak Detection – Web Server


Valve Leak Detection – SwanviewLX


Valve Leak Detection – SwanviewLX


NWS Valve Testing Data Exelon Generation Company LLC Lift NWS SWSNWS Technologies 4 13:56 17:56Hot Shop 2 5 14:06 18:06

6 14:16 18:16

Sen 1A Pilot Sen 4A Main Sen 2A 2nd Stage Sen 1B ExhaustDATE SWE VALUE LIFT # DATE SWE VALUE LIFT # DATE SWE VALUE LIFT # DATE SWE VALUE LIFT #

5/23/2013 17:56 85 5/23/2013 17:56 23 5/23/2013 17:56 37 5/23/2013 17:56 245/23/2013 17:56 23 5/23/2013 17:56 19 5/23/2013 17:56 35 5/23/2013 17:56 225/23/2013 17:56 28 5/23/2013 17:56 32 5/23/2013 17:56 36 5/23/2013 17:56 205/23/2013 17:56 21 5/23/2013 17:56 19 5/23/2013 17:56 35 5/23/2013 17:56 215/23/2013 17:57 28 5/23/2013 17:57 21 5/23/2013 17:57 41 5/23/2013 17:57 205/23/2013 17:57 22 5/23/2013 17:57 19 5/23/2013 17:57 42 5/23/2013 17:57 215/23/2013 17:57 23 5/23/2013 17:57 20 5/23/2013 17:57 46 5/23/2013 17:57 205/23/2013 17:57 21 5/23/2013 17:57 30 5/23/2013 17:57 34 5/23/2013 17:57 225/23/2013 17:58 19 5/23/2013 17:58 19 5/23/2013 17:58 34 5/23/2013 17:58 225/23/2013 17:58 30 5/23/2013 17:58 19 5/23/2013 17:58 34 5/23/2013 17:58 205/23/2013 17:58 23 5/23/2013 17:58 20 5/23/2013 17:58 36 5/23/2013 17:58 205/23/2013 17:58 32 5/23/2013 17:58 22 5/23/2013 17:58 34 5/23/2013 17:58 205/23/2013 17:59 22 5/23/2013 17:59 20 5/23/2013 17:59 34 5/23/2013 17:59 205/23/2013 17:59 23 5/23/2013 17:59 25 5/23/2013 17:59 34 5/23/2013 17:59 215/23/2013 17:59 23 5/23/2013 17:59 20 5/23/2013 17:59 34 5/23/2013 17:59 205/23/2013 17:59 25 5/23/2013 17:59 20 5/23/2013 17:59 34 5/23/2013 17:59 205/23/2013 18:00 19 5/23/2013 18:00 19 5/23/2013 18:00 33 5/23/2013 18:00 205/23/2013 18:00 19 5/23/2013 18:00 19 5/23/2013 18:00 34 5/23/2013 18:00 205/23/2013 18:00 21 5/23/2013 18:00 19 5/23/2013 18:00 35 5/23/2013 18:00 205/23/2013 18:00 19 5/23/2013 18:00 19 5/23/2013 18:00 33 5/23/2013 18:00 215/23/2013 18:01 11263 5/23/2013 18:01 11266 5/23/2013 18:01 33 5/23/2013 18:01 23475/23/2013 18:01 552 5/23/2013 18:01 737 5/23/2013 18:01 11262 5/23/2013 18:01 23475/23/2013 18:01 284 5/23/2013 18:01 141 5/23/2013 18:01 295 5/23/2013 18:01 1585/23/2013 18:01 296 5/23/2013 18:01 128 5/23/2013 18:01 138 5/23/2013 18:01 1585/23/2013 18:02 296 5/23/2013 18:01 124 5/23/2013 18:01 227 5/23/2013 18:01 415/23/2013 18:02 62 5/23/2013 18:02 244 5/23/2013 18:02 164 5/23/2013 18:01 485/23/2013 18:02 32 5/23/2013 18:02 329 5/23/2013 18:02 78 5/23/2013 18:02 335/23/2013 18:02 38 5/23/2013 18:02 26 5/23/2013 18:02 45 5/23/2013 18:02 255/23/2013 18:03 29 5/23/2013 18:02 22 5/23/2013 18:02 49 5/23/2013 18:02 235/23/2013 18:03 26 5/23/2013 18:03 25 5/23/2013 18:03 41 5/23/2013 18:02 335/23/2013 18:03 39 5/23/2013 18:03 46 5/23/2013 18:03 72 5/23/2013 18:03 225/23/2013 18:03 28 5/23/2013 18:03 22 5/23/2013 18:03 41 5/23/2013 18:03 245/23/2013 18:04 24 5/23/2013 18:03 21 5/23/2013 18:03 46 5/23/2013 18:03 245/23/2013 18:04 25 4 5/23/2013 18:04 26 4 5/23/2013 18:04 43 4 5/23/2013 18:03 21 45/23/2013 18:04 24 4 5/23/2013 18:04 27 4 5/23/2013 18:04 40 4 5/23/2013 18:04 22 45/23/2013 18:04 25 4 5/23/2013 18:04 21 4 5/23/2013 18:04 53 4 5/23/2013 18:04 21 45/23/2013 18:05 35 4 5/23/2013 18:04 24 4 5/23/2013 18:04 49 4 5/23/2013 18:04 21 45/23/2013 18:05 51 4 5/23/2013 18:05 23 4 5/23/2013 18:05 75 4 5/23/2013 18:04 28 45/23/2013 18:05 36 4 5/23/2013 18:05 26 4 5/23/2013 18:05 46 4 5/23/2013 18:05 23 4


NWS Valve Testing Data

Is the valve leaking: YES or NO? YES: How much is the valve leaking?

The Stresswave Energy (SWE) metric is able to quantify valve leakage

Leakage can be recorded, tracked and analyzed NO: How tight is the seal?

Improve maintenance techniques


NWS Valve Testing Data

SWE = Stresswave Energy Total stress energy contained within sensor signal

Sigma = Standard Deviation Amount of variation from the average

UCL = Upper Control Limit Statistical distribution limit of the SWE level of the tested

valve


Scientech Report


NWS Valve Testing Data Comparison – Reheater Valve

Lift #1 Lift #2 Lift #3

Lift #5 Lift #4

Sensor Location SWE AVG 1 Sigma UCL Status

Main 2C 40 19 96 PASS

New Valve Passed Scientech Test on Lifts #4 & Lift #5 with Good Results & Passed Cold Bar Test due to NWS lapping prior to RV test.


NWS Valve Testing Data Comparison – Reheater Valve

Lift #1 Lift #2

Sensor Location SWE AVG 1 Sigma UCL Status

Main 2C 539 543 2169 FAIL

Valve did not lift

Valve did not lift

New Valve Failed Scientech Test on Lifts #1 & Lift #2 with High Results & Failed Cold Bar Test due to poor lapping at OEM with some NWS Lap prior to RV test.


NWS Valve Maintenance – TR SRV


First Two Lifts were OK, and Lift #3 Failed Cold Bar Testing

TR 3-stage SRV has 5 Scientech Sensors - Lift #3 shows the Main seat is not closing smoothly in a just refurbished valve.


NWS Valve Test after Maintenance – TR SRV Failed Scientech

Two automatic lifts were performed and leakage was detected at ~750psig

The valve was fully disassembled for repair The main piston rings were found to have scoring marks

and were replaced The main seat and disk were lapped again and the SRV

was placed on the steam test cell for As-Left Certification


NWS Valve Test after Maintenance – TR SRV Passed Scientech


AFTER

After SRV maintenance to replace the Main seat rings and some lapping, the SRV Passes three final As-Left Certification Lifts & Cold Bar Testing during Lifts #5, #6, & #7.


NWS Valve Testing and Maintenance – SRV

Scientech Stresswave technology can “hear” valve leakage.

Exelon developed software calculations with Scientech that can: Reliably identify quality valve performance Quantitatively measure valve leak magnitude Predict valve integrity and future performance

Exelon checks that the UCL values for the seats are within the normal range

The ASME Cold Bar is still the final acceptance criteria


Conclusion

Questions/Comments


http://scientech.cwfc.com

Sal Tareen Engineer, Senior [email protected] |

mailto:[email protected]

Documents

Scientech Stresswave SRV Leak Detectionfamos.scientech.us/PDFs/2015_Symposium/Scientech... · Scientech Stresswave SRV Leak Detection ... Piezoelectric accelerometer ... Valve Leak